How to Design a Custom Exhaust System

[Jafa]

Agreed, nice write up with some good information.

Question if I may, on the website it gives pipe diameter for approximate horsepower, but that's for v8's. What pipe diameter would you recommend for a 4 cylinder, race-only ( road course ) engine putting out 180hp at the flywheel. 12:1 compression ratio, running straight avgas ( piston aeroplane engine fuel ). Car weighs 2300lbs.

Thanks in advance.